How to update window.location = "xtk:setDirty:true" from a custom made jssp?

I see that in OOTB jssp pages, in lot of places window.location property has been used where there are setting up xtk object values. For example, i see that in aemContentPicker jssp code, xtk:setDirty:true is used but however when i try to do the same from a custom jssp for a specific use case, i couldn't update/set this. 

I also searched for this xtk:setDirty in all places but couldn't find where it is defined in ACM.

Have anyone used this before and any idea how to setup these from a custom jssp?